Intermediate steps of the continuum subtraction method described in Section 2.2. The top panel shows the final Savitzky–Golay filter (green) on the filtered line spectrum (black) and the filtered lines (light grey). The middle panel displays the residuals (black; line-filtered spectrum after subtracting the Savitzky–Golay filter), together with their -3×STD level (green), and the data points that fall below the -3× level (red crosses). The bottom panel shows the full JWST-MIRI spectrum (black) together with the estimated baseline (green) and the data points that have been masked throughout the estimation of the baseline (red crosses).